NO, You don't seem to understand. Taxes that are imposed on the employer, are just another cost of employing....like salary. In terms of calculating an absorption rate....the nature of the cost is immaterial....as long as you have estimated the total costs correctly. The distinction is immaterial.
I understand perfectly well that income taxes are NOT a factor of production no matter how you might torture the concept. They are neither Land, Labor or Capital. Costs come from those factors and nothing else.
Again you refuse to seperate income taxes from payroll taxes which ARE an aspect of Labor costs.